Sea birds (usually guillemots), chough and occassionally Peregrines have been known to nest on Main Cliff and don't seem to be bothered by climbers. Having said that, it is best to avoid the route Pentathol from March 1st until July 31st, due to nesting Guillemots, as it is very unpleasant to climb at that time and birds could be disturbed.
In 2018 a pair of Peregirnes nested on the first traverse pitch of the route Cordon Bleu and that route and the routes immediately surrounding, it were subject to a climbing restriction. If the birds return this year, this restriction will be applied again - look out for on-site signs at the gearing up spot/descent gully.